The substation is the heart of an offshore wind farm and works like a “power socket”: This is where the generated electricity flows together, is transformed and sent ashore via a converter platform.
What’s special about the substation at Trianel Wind Farm Borkum is that it also serves as a transformer platform for its sister wind farm, Trianel Wind Farm Borkum II.
One substation, two wind farms. The effective and successful logistics concept optimises energy generation and reduces costs. The farm-internal platform is operated by Infrastruktur Windkraftwerk Borkum GmbH & Co. KG (IWB).
Mastering daily requirements
IWB’s task is to maintain the availability of the substation at all times in order to permanently guarantee the conversion and feed-in of the electricity generated in the offshore wind farm.
The substation consists of many individual components and assemblies that are all important in themselves.
The two main transformers are essential for power generation. Furthermore, there are three large emergency power systems on the substation, which supply both the substation and all wind turbines with energy in the event of a grid failure. Other components include the five-ton platform crane, various rescue equipment, a helicopter landing deck, the fire protection system, telecommunications systems, etc.
Daily tasks of IWB staff consist of planning and carrying out technical maintenance and servicing of these components, as well as organising offshore operations. In addition, monitoring of regulatory requirements, occupational health requirements as well as safety and environmental protection are part of the daily work.
So it is not only important to ensure the capacities of technical components and their functionality, but also to adhere to a structure that covers operator responsibility and guarantees daily and long-term safeguarding of the investment. All activities in and around the wind farm have to be controlled, analysed and documented.
Individual wind turbines of an offshore wind farm are usually divided into clusters. Wind turbines in each cluster are connected to each other by submarine cables (inner farm cables) which are laid in a ring or radial pattern within the wind farm leading to the substation. The inner park cabling also belongs to IWB.
Heart of the wind farm
The substation serves to reduce the losses and expense of transmitting electrical power from the offshore wind farm to the mainland. It transforms the (AC) voltage generated by the wind turbines from 33 kV to 155 kV via two export transformers. This energy is then transmitted by export cable to the DolWin alpha converter station for high voltage direct current transmission to shore.
The substation is designed for both Trianel offshore wind farms with a total capacity of 400 MW. The electrical design of the two offshore wind farms is such that the substation, wind turbine and inner-farm cabling components are optimally coordinated to meet grid compliance requirements for feeding the generated electricity into the public power grid.
For this purpose, the substation is founded on a jacket construction, where the upper part is called the topside. The topside can be accessed via two boat landings attached to the jacket or via the helicopter landing deck.